1. Filed of the Invention
The present invention relates to warning or alarm systems and, more particularly, to an electrical device of variable size for use in signalling the presence of unwanted substances near sensitive equipment.
2. Description of the Relevant Art
Heretofore, there have been various means for signalling the presence of liquids.
U.S. Pat. No. 2,127,538 discloses a device for use in determining the presence of moisture in a child's bed. A series of wires are provided on a mat. When moisture contacts two wires, a relay switch is closed and an alarm, either audible or visual, will be activated.
This device cannot be varied in size since cutting of the device can result in the cutting of wires and shorting of the device.
U.S. Pat. No. 3,986,110 discloses a device for determining the depth of a liquid accumulating on its surface. The device is constructed of a non-conductive material with a web of elongated strips of foil. The device operates such that the presence of liquid affects the capacitance and conductance of the sensor.
Again, this device cannot be adapted to situations other than that discussed above.
U.S. Pat. No. 4,083,038 discloses a sensor for determining the level of a liquid in a container. The device employs a web of non-conductive material with electrically conducting plates spaced therein. As the liquid level in the container drops, the capacitance of the device changes to cause an alarm to be given.
The present invention provides a device capable of being sized and shaped for the given situation on site. In addition, the device is lightweight and easily transportable.